The speed at which tape drives are able to write data is dependent on the amount of compression that the drive is able to generate. Please see tech note 004 on data compression for further information.
Generally, the more compressible the data, the faster the drive can write it.

Drive speed is also affected by file size. When writing files to tape, the controlling software has to open each file before it is written, in order to access the data inside. When backing up a large number of small files, the software must open a file, write the small data in it, close the file, then open the next file and so on. When writing large files, the process of actually transferring data to tape comprises more of the actual backup process, and the average speed of the drive increases dramatically.
Generally speaking, if the data set contains a large number of small files the drive speed will be lower than when backing up a data set comprising a few very large files.
If you think that a drive is writing at a speed slower than it should, try testing it with a data set made of large, compressible files. This will enable you to determine if the drive is capable of writing at higher speeds.

High Speed Support
By default, FlashNet writes in single threaded mode. In simple terms, this means that one single connection with the drive is used to both read and write (every backup uses both read and write processes). This is fine for drives with a maximum speed of around 12-14Mb/s.
If your drive is capable of writing at speeds greater than 15Mb/s, single-threaded operations may not be able to drive the device at maximum speed. For higher-speed devices, FlashNet has an option called High Speed Support. When enabled, this option allows FlashNet to use multi-threading, which uses several concurrent 'connections' to the drive, allowing it to write at much greater speed.
Contact your AXI for details on purchasing the High Speed Support option.

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